Fire bridge



y 31, 19321 D c. H. GREVE ET AL 1,861,388

FIRE BRIDGE Filed Feb. 2, 1929 Patented May 31 1932 UNITED STATES CARL HEINRICH GREVE, 0F ALTONA-ON-ELBE, AND WALTER CHRISTIAN IbETLEF PATENT oFF'rc-a 7 SCHWARZ, 0F HAMBURG, GERMANY, ASSIGNORS TO THE FIRM OF ROLF-S KOHLEN- OXYD-VERBRENNER GESELLSCHAIT MIT BESCHRANKTER HAF' IUNG, OF HAMBURG,

GERMANY FIRE BRIDGE Application filed February 2, 1929, Serial No.

The invention relates to improvements in fire bridges formed with passages for introduction to the furnace of preheated secondary air whereby to ensure complete combustion of the incompletely consumed gases passing over the fire-bridge, particularly the carbonic oxide contained in these gases.

The novelty of the invention resides in the feature that the passages are helically formed, that is, are each twisted about an axis extending longitudinally of such passage. As has been determined, by this arrangement certain movements are lmparted to the air flowing through the passages whereby there is effected intimate mixture of the preheated air with the unconsumed particles of the gases above the bridge, in consequence of which complete combustion of the latter is secured, and thus the formation of a blue flame, such as created by a blow pipe, is avoided. The passages, which in horizontal cross-section are oblong or oval, may be reduced from the air entrance up to the exit.

There may be provided at least two groups of passages having adjacent exit openings, the passages of one group being twisted in the opposite direction to those of the other group.

In the accompanying drawings a furnace fitted with a fire bridge constructed according to the invention is illustrated by way of example.

Fig. 1 is a partial section of a furnace flue with fire grate and a hollow fire bridge, constructed in accordance with the invention.

Fig. 2 is a plan of the fire bridge,

Fig. 3 a section drawn to the line 3-3 of Fig. 1, and

Fig. 4 a section drawn to the line 44 of Fig. 1, and

Fig. 5 is an inverted plan of the fire bridge.

\Vithin the flue 7 is disposed a fire bridge extending to a higher level than the grate 2 and comprising a hollow casting 3 having external ribs 4 and 5 and a fire-proof facing 6 next to the grate. The casting 3 may be integral with the support 7, or mounted on top of such support, said support 7 having an opening 8 adapted to be closed by a damper 12, which can be controlled by a link and 836,996, and in Germany February 18, 192 8.

lever system 9, 10, 11 operated from outside the furnace.

The hollow interior of the casting 3 is subdlvided by partitions 13, forming intermedi-- ate passages or ports 14. These partitions, which extend from the front wall to the'back Wall may be replaced by ribs which branch off alternately from 'one wall and the other and interenga-ge oneanothera The passages 14 terminate-at the bottom inslots 15, which preferably extend parallel to the grate bars. At the upper end of the fire-bridge the passages 14 terminate in slots 16. Thus, the passages are of tapering cross-section from the bottom to the top. Further, the passages 16 are twisted, merging by degrees from the position of the slots 15 parallel to the grate bars into the position of the slots 16 at an angle thereto.

From Figs. 2, 3, 4 and 5 it will be seen how for this purpose the partitions 13 change by degrees their angular position. The consequence is that the air regulated by the damper 12 and entering the opening 8 is given in its flow through the passages 14 from the openings 15 up to the openings 16 a helical motion such that it escapes from the openings 16 as a sheet and is therefore thoroughly mixed with the hot gases. The arrangement may be such that the passages 14 comprise two groups, as shown, the passages of one group being twisted in one direction, and the passages of the other group being twisted in the other direction. Accordingly, as may be gathered from Fig. 2, the upper openings of the two sets 16 are oppositely angled, and two air vortices of opposite hand are set up. If desired sub-division of the set of passages into groups may be resorted to, so that there are set up three or more vortices which may be of different inclination.

We claim 1. A fire bridge for furnaces comprising a support having an aperture therethrough, a casting mounted upon said support having passages therethrough oblong in cross-section and communicating with said aperture at their lower ends and opening out at their upper ends approximately at right angles to the direction of the gases of combustion,

the walls of said passage being twisted about the approximately vertical center line of the passage.

2. A fire bridge according to the construction setforthjri niclaim 1 in -w'hich the passages taper f'i'omwh'e poinfiat whiclrthey'have communication with the aperture in the-support to the top of said casting,

'32 A fire Bridge for furnacesfcoinprising a support" having an aperture t'herethrough a eastin'g'inount'ed upon said support having passages therethrough of oblong cross-section and communicating with said aperture at their lower ends, andopening out at their upper ends at an angle to their lower ends, flildxOQItili-IL of said'passageslhaving their outilet openings disposed at an angle to other out-let openings to cause a more thorough mixing: of the air passingthrough: said: pas,

sagesuvit-h: the: incompletelyconsumed gases passing oven the fire bridge.

, Ian testimony whereof we havesigned our names to this specification;

CARL HEINRICHJGREVE. W-AbT-ERI CHRISTIAN- DETLEF- SQHW-ARZL 

